Project Summary
Climate change continues to result in increased exposure to wildfires in California (CA) and around the
world with smoke reaching far more populations than in recent years. There is increased concern for the health
effects of these fires, especially for pregnant people and their developing embryos/fetuses. Birth defects are
the leading cause of infant mortality in the US. In the US, 3-5% of all births, i.e., more than 100,000
babies/year, are born with a major birth defect. Few studies have been conducted to examine the relationship
between wildfire smoke and birth defects, and none have included study populations with detailed wildfire
smoke exposure metrics. None have included large population-based studies with thorough case
ascertainment.
We propose to compile a unique group of datasets of fire occurrence, air quality monitoring and modeling,
meteorology and housing characteristics of the maternal residence during critical periods of pregnancy for
mothers of children with and without birth defects in the National Birth Defects Prevention Study (NBDPS) and
Birth Defects Study To Evaluate Pregnancy exposureS (BD-STEPS) Study, observational, population-based,
case-control studies, between 2000-2018 in California. Cases had at least one of 22 major birth defects of the
heart, brain and spine, eye, ear, face and mouth, gut, or muscles and bones. Detailed residential history and
covariate data are available from extensive interviews of participants about their pregnancy experience and
general health, and medication use during pregnancy. Specifically, we aim to estimate the risk of 22 major
structural birth defects in relation to wildfire smoke exposures (fire burned area within 20 and 50km, smoke
frequencies, fire-sourced PM2.5 and ozone, and polycyclic aromatic hydrocarbons) at the maternal residence in
early pregnancy during defect-specific periods of development. Additionally, we will investigate whether the
relationship (or lack thereof) between wildfire smoke exposure and birth defects is modified by neighborhood
socioeconomic status, psychosocial stress or housing factors.
With geocoded residential history, physician determined case ascertainment, extensive covariate
collection, housing characteristics and exhaustive air pollution and fire measurement and modeling, our study
will have the most precise exposure assessment and case ascertainment to date in a highly exposed region of
CA. The findings have the potential to inform targeted clinical and public health interventions designed to
reduce exposures to pregnant people.